1. Field of the Invention
This invention relates to a structure for fixing an optical member to a holder, and more particularly to a structure for fixing an optical member to a holder by adhesive.
2. Description of the Related Art
As disclosed, for instance, in Japanese Unexamined Patent Publication No. 62(1987)-189783, there has been known a solid state laser in which a Nd-doped laser crystal is pumped with a semiconductor laser.
In such a solid state laser, an optical member such as an etalon is often provided in a resonator in order to make the oscillation mode a single longitudinal mode or to control polarizing direction.
A relatively small optical member such as an etalon is generally fixed to a holder which is larger than the optical member in size and is held in a predetermined position. FIG. 4 shows a conventional structure for fixing an optical member 2 to a holder 1. As shown in FIG. 4, in the conventional structure, the optical element 2 is bonded to the holder 1 substantially along the entire surface 2a facing the holder 1 except the portion opposed to an aperture 1a of the holder 1. The hatched portion in FIG. 4 represents the bonding area.
Though being simple, the conventional structure is disadvantageous in that the optical member can be deformed (warped) or broken when subjected to a temperature change due to difference in the linear expansion coefficient between the holder and the optical member. This problem is especially serious when the optical member is relatively small in thickness like the etalon or the optical member is apt to generate cleavage.